JPH0261866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming an internal tooth profile with a bottom by forging.

(Prior art) As this type of method, for example, Japanese Patent Publication No. 58-48258
As described in the publication, there is a method in which a tooth-shaped punch is pushed into the inner periphery of a cup-shaped material to perform extrusion molding, a method in which the upper surface of a solid material is extruded with a tooth-shaped punch and extrusion molded, or the inner periphery of a cup-shaped material is A method is known in which the outer periphery of the material is constrained with a toothed punch and the outer periphery is pressed to form the material.

(Problems to be solved by the invention) However, with the push-in type, there are restrictions on the shape, and not only is it impossible to obtain the effective part of the teeth all the way to the bottom of the inner periphery, but the punch wears out significantly and the life of the punch is short. In addition, the extrusion method requires a high forming load, and forming by cold forging with a particularly large diameter tooth shape is not only not a good idea as it increases the size of the press.
The problem is that the distortion is large and the wear of the punch becomes even more severe.Also, the ironing method is advantageous in terms of punch wear, but if the internal tooth profile is large and the tooth height is high, the movement of the meat due to the outer periphery ironing. However, there were problems such as the teeth not being completely formed because the water flowed exclusively in the vertical direction and did not approach the inner periphery.

(Means for Solving the Problems) The present invention is aimed at solving the above problems, and a cup-shaped material is attached to a lower punch that is biased upwardly within the die via a spring. Set the material with its open end facing downward so that the peripheral wall of the material fits onto the lower punch, and lower the upper punch while holding the bottom plate of the material between the upper punch and the lower punch. The material is pressed down and extruded by passing it from the open end through a die orifice formed in the die that has a smaller diameter than the outer diameter of the material, and forms an internal tooth profile by imitating the tooth profile provided on the outer periphery of the lower punch. It is characterized by the formation of

(Example) The method of the present invention will be explained below based on an example. Fig. 1 shows an example of an apparatus for carrying out the method of the present invention. It consists of a die 4 that is attached through the holes 3 and 3, an upper punch 5 that is inserted and inserted into the die 4 so as to be freely removable and removable, and a lower punch 6 that is installed inside the die 4. 6a
At the same time, the lower punch 6 has a cup-shaped material 7 set therein with the open end facing downward.
However, when the open end of the material 7 is extruded with the bottom plate being held between the upper punch 5 and the lower punch 6 during the processing described later, the flow rate of the material is lower than the downward movement speed of the upper punch 5. In order to prevent the upper punch 5 and the lower punch 6 from lowering the gripping force of the bottom plate of the material 7 by lowering the lower punch 6 due to the friction caused by the speed difference, from the beginning of the forming process. Until the end, the lower punch 6 is supported by a pressure-receiving plate 8 whose pressure-receiving area is enlarged so as to be in close contact with the bottom of the cup, and the plate 8 is inserted into the die holder 1 via a urethane spring 9 so as not to be subjected to a large molding load. Floating supported. Note that it is not preferable that the clamping force of the bottom plate of the material 7 between the upper punch 5 and the lower punch 6 decreases during forming because the bottom plate will buckle in an arc shape and an accurate tooth profile will not be formed. A die orifice 4a having a smaller diameter than the outer diameter of the material 7 is formed inside the die 4. In the figure, 10 indicates a knockout, and 11 indicates a positioning notch for the urethane spring.

The processing method using the above-mentioned apparatus will be explained with reference to FIG. 2. As shown in FIG. 2a, the cup-shaped material 7 is set on the lower punch 6 with its open end facing downward, and then as shown in FIG. 2b. upper punch 5
When the bottom plate of the material 7 is held between the upper punch 5 and the lower punch 6 by moving the lower punch 6 downward, the lower punch 6 tightly contacts the bottom surface of the cup due to the elastic force of the spring 9 and restrains the inner periphery.
While the bottom plate is restrained by the lower punch 6, when the upper punch 5 is further moved downward as shown in FIG. , internal teeth are formed on the inner periphery of the material 7, following the tooth profile of the outer periphery of the lower punch 6. Next, as shown in FIG. 2d, the upper punch 5 is raised and the lower punch 6 is
is raised together with the workpiece to its set position, and then the workpiece is removed from the mold by knockout 10 as shown in FIG. 2e.

(Effects of the Invention) According to the present invention, a cup-shaped material is set in the lower punch 6 which is floatingly supported within the die 4 via a spring 9 with its open end facing downward, and the material 7 is The bottom plate is held between the upper punch 5 and the lower punch 6 and extruded from the open end of the cup, and internal teeth are formed to follow the tooth profile provided on the outer periphery of the lower punch 6. The material 7 can be molded without buckling its bottom, making it possible to form a more accurate bottomed internal tooth profile with less distortion, as well as reducing wear on the lower punch 6 and improving mold life. It has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a schematic diagram showing the processing steps. 4...Die, 5...Upper punch, 6...Lower punch, 6a...Tooth profile, 7...Material, 9...Spring.

Claims (1)

[Claims] 1. Set a cup-shaped material in a lower punch that is biased upwardly in the die through a spring, with its open end facing downward, so that the peripheral wall of the material fits externally into the lower punch, and While holding the bottom plate between the upper punch and the lower punch, lower the upper punch to push down the material, and insert the material into the die orifice formed in the die, which has a diameter smaller than the outside diameter of the material, at its open end. A method for forming an internal tooth profile with a bottom, characterized in that the internal tooth profile is formed by extrusion molding by passing the punch through the bottom punch, and forming the internal tooth profile by imitating the tooth profile provided on the outer periphery of the lower punch.